let test = 88
// 匿名函数自调用
;(function (window,undefined) { 
    function init(el){
        let els = document.querySelectorAll(el)
        for(let i=0;i<els.length;i++){
            this[i] = els[i]
        }
        this.length = els.length
    }  
    let jQuery = function (el) {
        return new init(el)
    }
    jQuery.extend = function(object){
        for(let key in object){
            init.prototype[key] = object[key]
        }
    }
    init.prototype = {
        css(cssAttr,cssVal){
            for(let i=0;i<this.length;i++)
            {
                this[i].style[cssAttr] = cssVal
            }
            return this
        }
    }
    window.jQuery = window.$ = jQuery
})(window)
let jqObj = $('div')
console.log(jqObj)
jqObj.css('color','green').css('background','pink')
$.extend({
    bg(){
    }
})
console.log($('div'))
  